REVIEW: Magnaflow "California" Replacement Catalytic Converters - M3

[LuxoM3]

UPDATED: My car has picked up A LOT of torque in the replacement of the cats. If you feel your 95 is lagging a bit and have done the other stuff like new fuel filter, pump, crank sensors, etc. This cat replacement is a REALLY good upgrade to the stock cats. Also, my average gas mileage has picked up from 20-21 to 22-23!

There are TWO cats under the car that were replaced. This is NOT a single cat conversion - illegal in CA.


So after going through the hell that is California SMOG, I thought to share some of my experiences with you guys.

SMOGGING THE CAR
Stock 1995 BMW M3, 188k miles on motor - new plugs, O2 sensor, and newer intake, timing, etc. sensors. Oil, filter and air filter changed. And YES, the cats were HOT... come on guys, I've been on this board 10 years now...

15 mph: HC 123 (max 85), CO .32 (max .50), NO 833 (max 695)
25 mph: HC 50 (max 50), CO .15 (max .47), NO 492 (max 717)

The main issue here is unburnt fuel (HC) and Nitrous Oxide (NO) which sometimes is the temp of the combustion chamber, but if both the HC and NO are high, the catalytic converter isn't working. In my case, it wasn't converting the unburnt fuel molecules, and was just cooking - hence high NO. Think of a bad cat like a hot boiling fuel soup.

MAGNAFLOW
So Magnaflow makes a California SMOG-approved Catalytic converter - part #36004
(http://www.magnaflow.com/02catalytic...niversal=36004).

It's a universal deal, but the fit and finish is good and it welds up nicely.
Magaflow retails the Cats for $410 for the set of TWO
UPDATED 3/2012 - Looks like Magnaflow wants $600+ now. :\

For reference - BMW will sell you the ENTIRE CAT system for $2300 retail. OEMBMWParts.com (something like that will sell it to you for $1300). Bavarian Autosport sells DAC CAT Systems for $750-ish.

$1300 wasn't bad for a new stock system. But installation and shipping would add an easy $300 to $400 to that price.

The DAC is a good price, but the warranty of two years sucks. We have smog every 2 years so what's the point of that?

After reading some reviews with Magnaflow on other car boards like Honda and Toyota, I pulled the trigger with another muffler shop near me in Dublin CA. (Scott's Minute Muffler - yelp him. Solid 5 star reviews).

Long story short, Scott got me the cats AND installation for $400 ($429 with tax). Yes, I got parts and labor for less than retail!

Ok so +1.

I drove the car for about 5 days to get a few miles on the cats for SMOG. About 250 miles in my case.

Before my SMOG, I did a 20 mile round trip to make sure all systems were warm. I pulled into the smog shop at 3pm. It was about 67 degrees outside.

Here's the results...

15 mph: HC 59 (max 85), CO .06 (max .50), NO 10 (max 695)
25 mph: HC 22 (max 50), CO .02 (max .47), NO 5 (max 717)

The drops are pretty staggering.
1. The HC's dropped in half - obviously the catalytic converting the unburned fuel.
2. The Carbon Monoxide dropped by 500%+
3. The Nitrous Oxide dropped by 500%+

+2

And for the final bonus...
1. 5-year, 50,000-mile external warranty; 25,000-mile internal warranty
2. Cost $410 retail for the set of two (online price is $150/unit or $300 set)
3. Performance? Put it this way... my highway torque picked up A LOT.
4. No more stupid 2500rpm cat rattling!

I had to sell my TRM chip, intake, HFM, and injectors to help finance this replacement (got some monster bills this month), but given that my stock cats weren't flowing as well, installing the Magna ones helps make up that feeling of the power I lost.

In short
I'm pretty stoked. I saved an easy $800 over the best price I could find over the stock system, got back some lost power, and passed smog with numbers only new cars see.

IF YOU decide on this route, the 36004 cats run be gotten online for about $150 each, or $300 set. Magnaflow suggest $410 retail for both, so if you can get the whole thing ordered and welded onto your car for $450 or below, that's a decent price.

Oh and bad news... this option is pretty much only for the 95 M3s. The 96+ OBD2 cars don't have this option.
( Updated 3/2012 - Magnaflow now lists a cat replacement for 96+ cars. CARB Cert/ok)


UPDATED:

Here's how it looks - it's a tight fit, but note how the welding guy added some piping to ensure best flow and fit...

[Volf]

Glad you got it sorted out.

[LuxoM3]

Thanks Volf - man I was crying like baby weeks ago. There's nothing like getting the car running *right* and set-up how you like, only to be confront with emission issues. :|

[fun2drive]

Good data for all of us. My cats are really old on my M3 vert and I would not be surprised if a new set of these welded on would not improve performance some given there has to be some back pressure.

[cmzwirner]

Glad you fixed it! My car is throwing a few CEL's at the moment. Something along the lines of a bank right and bank left. If its due to the cats, ill be going this route.

[LuxoM3]

Well for OBD2 cars, it's pretty much always the O2 sensors. If they have more than 75k miles on them... they can be iffy. The stock ones on my 96 only lasted until 55k before they started not working right.

[froggy47]

Thanks for posting, I just barely got by on NO a couple of weeks ago. Pretty sure I'll have to cat it to pass in 2 more years.

[sennasixty8]

Congrats, Luxo-man!

When I did this same thing (minus the pre-smog drama, on an e30 I once had) I felt a huge load lifted off my back.

Enjoy the relief, and get out and drive that thing... (but gas is xpen$ive).

[Relax]

Great review, I take it that your mid-section was modified to house a single cat? Do you have any pictures of the final product?

[froggy47]

Me too, got a pic of the exhaust?

[wolffbimmer]

Dang, my car has similar mileage with stock cats. That's a huge decrease in numbers. Glad you got her all fixed up.

[pig4bill]

Did you have any trouble with the visual inspection? Do these need a CARB number?

Did you pass at a test-only station? I'm going to have to deal with this soon.

[doofoo]

Also interested in how you piped these guys in. I need to install some cat's in my ebay longtube + full exhaust setup. Wondering if you had it step down to 1 cat then back out, or 2 individual cats?

[GREENMOBSTER]

I have a 95 M3 and I think the CAT is done for. My car smells while I drive and stinks when I get on it. I dont have to do emissions where I live, but will this be good for me just to fix it or should I go stock? Sorry to hijack.

[mweinst]

Just curious, did you do the initial smog with the TRM chip and goodies? I wonder how much of the change came from the cat alone?

[EURO M3 CSL]

subscribed

[LuxoM3]

I'll get pics as soon as the weather clears up... but in a nutshell...

1. MY set-up KEEPS the dual CAT configuration. Scott at Minute Muffler just cut the old ones out (two of them) and welded the new ones in. He does A LOT of custom car work, so the welds are super sharp and clean. I'll get pics up when I can get under the car.

2. SMOG - these are CARB approved units. In CA, an exhaust shop WILL NOT TOUCH replacement cats if they are not approved (i.e. in a box, new, with CARB docs, etc.)

And as a footnote, an exhaust shop OR any other car place won't even put in a used system. I have good friends at EDGE and BILL ARNOLD up on the north bay - if you get nabbed by the smog police, they will demand names. It's pretty crazy what goes on with exhaust work. So I didn't want to put my friends in that position if it came down to ugly.


3. BEFORE - yep I was getting the rotten egg smell since about 120k. I BARELY passed smog at 140k. I'm at 188k now.

4. TRM CHIP - I sold all that stuff, but I did do the initial test with the TRM chip and it was comparable to stock. So yes, you can probably get by with it.

5. I tested at a CALIFORNIA SMOG station (Gold shield, whatever) - so about as stringent as it gets. They didn't care about CARB stickers on my car quite frankly. I had failed there twice already so when I walked in and said, I replaced the cats, the guy shrugged and said ok. Let's run it.

But keep in mind, I'm 41. I've got a kid's seat in the back seat and I talk like the manager at a Noordstroms so I don't get the "kid" treatment too often when I walk into a shop. :P

[GREENMOBSTER]

Yea, my car stinks inside while im driving, and has rotten egg smell. I dont have any leaks from what I can tell so the cat must be the culprit.

[IVAD32]

I went through this same hassle last year @120k. I ended up replacing the entire mid-pipe with a DEC unit from Discount Catalytic converters http://www.discountcatalyticconverte...nts=partfinder

The cost was $560 with shipping. They were a PIT to install and required some serious elbow grease to align.

With my new cats, my numbers were significantly better, and yet I barely passed HC.

@15 MPH
HC went from 189 --> 83 (max allowable 85)
CO went from 0.46 --> 0.04 (max 0.50)
NO went from 1775 --> 54 (max 695)

@25 MPH
HC went from 49 --> 23 (max allowable 50)
CO went from 0.12 --> 0.02 (max 0.47)
NO went from 298 --> 13 (max 717)

Now that your car is stock, do you miss the power of your chip+intake+injector setup?

[pig4bill]

Thanks much, Luxom3. I live in the south bay, but for that price, I can take a little drive up to Dublin.

[breakfast]

the cat will last you about a yr...... trust me.

and by that I mean you likely wont pass tail pipe smog .
its that way with 99% aftermarket cats. OEM is king and contains way more platinum (and whatever else). You better source some used (decent shape) oem cats.

thats why I always keep/pick up oem cats for any car I have(if I dont have the oem ones installed). its the same story every time. Youll see

[bimdaddy50]

I'm Having same problem with smog.Everyone says replace cats shop says don't even bother with aftermarkets. So do I gamble I have got so much in to this car, rebuilt motor 3k the only place I fail smog at is the NO on the 15 mph

15 MPH HC 54 max /33 CO .05/ .11 NO 430 max /623
25 MPH HC 37 max /26 CO .47/.12 NO 717 max / 637
can get dec cats for 850.00 muffler shop says they cal weld so in for 500.00
or do an injector clean and hope it loosens crap in cat for 175.00. Any help would be appreciated

[LuxoM3]

I went through this same hassle last year @120k. I ended up replacing the entire mid-pipe with a DEC unit from Discount Catalytic converters http://www.discountcatalyticconverte...nts=partfinder

The cost was $560 with shipping. They were a PIT to install and required some serious elbow grease to align.

Now that your car is stock, do you miss the power of your chip+intake+injector setup?

IVAD - yeah I wasn't horribly excited about the DAC. I especially didn't like the 20k/2year warranty. That was a BIT TOO low for me.

Do I miss the TRM/Euro set-up? Yeah - but to be honest, it's easy to let ego get the best of us, so being down HP allows me to concentrate on my driving style more than trying to beat the guy in the Civic or Mustang. I'm still a rice-boy at times. :P

the cat will last you about a yr...... trust me.

and by that I mean you likely wont pass tail pipe smog .
its that way with 99% aftermarket cats. OEM is king and contains way more platinum (and whatever else). You better source some used (decent shape) oem cats.

thats why I always keep/pick up oem cats for any car I have(if I dont have the oem ones installed). its the same story every time. Youll see

Well I have to disagree... from what I gather the NEW OEM CAT can only offer a 50k/5 year warranty also, the same as the Magnaflow set-up.
Buying a used cat... well, can be a crap shoot. My old OEM cat was smelling at 120k... so I'd have to find one sub that mileage and HOPE I'm not getting screwed. So let's use NEW as a comparison...

The OEM unit is $1300. Say $1500 shipped.
The Magnaflow units are $420. Lets say $500 shipped and installed.

If my Magnaflows fail in two year (and I am under 50k miles) they are under warranty for a replacement. But let's say they fail in 4 years and I have to buy another unit, then I've spent $1000. Repeat to 8 years and my total bill would be about $1500 worst case (accounting for warranty replacements and buying 3 units). In 8 years I would have put 160k miles on my M3 which would also be the limit of the stock system.

So doing the math, you actually would break even - ASSUMING the Magnaflow units fail every 4 years.

But here's the thing, do I plan on keeping my M3 for another 8 years? I don't know. There's a plethora of issues beyond exhaust that can happen or cost more. So in short, economically, if someone can't see keeping their M3 for more than another 4 years, than $500 for these CARB certificated cats is actually a better economic decision.

I'm Having same problem with smog.Everyone says replace cats shop says don't even bother with aftermarkets. So do I gamble I have got so much in to this car, rebuilt motor 3k the only place I fail smog at is the NO on the 15 mph

15 MPH HC 54 max /33 CO .05/ .11 NO 430 max /623
25 MPH HC 37 max /26 CO .47/.12 NO 717 max / 637
can get dec cats for 850.00 muffler shop says they cal weld so in for 500.00
or do an injector clean and hope it loosens crap in cat for 175.00. Any help would be appreciated

BD - your NO is REALLY high. Should only be in the tens, not hundreds. HCs aren't too high, but your numbers are similar to mine.

What happens is the cat is trapping the fuel inside of it and it's boiling the fuel - this bring the HC numbers up (unburnt fuel) and NO up (temperature).

A good cat will keep flow to a maximum (brings the NO #'s down) and convert the unburnt fuel into vapor(? , not fuel).

I'd say go new cats.

The whole aftermarket cats are crap I think is leftover sentiment from the late 90s when everyone was buying aftermarket cats for performance. Then the new rolling dyno's kicked in and everybody was failing.

Magnaflow is a seriously reputable company and based on my financial stats... you can buy 3 Magnaflow cats for the price of the OEM one. The OEM one will get you a base 5 year/50k mile warranty which is the same warrantt as the Magnaflows.

If you did dollar to dollar, the Magnaflows would net you 15 years/150k miles of warranty if you bought one for every SMOG you failed outside of the warranty period.

So the question is, would you rather pay $500 now or $1500?

[2K6TBSS]

I would like to see some pics of the install.

Did you have to purchase 2 of the cats, or just 1?

[LuxoM3]

It's 2 cats under the car. You can't do a single cat in California if your car came with one.